Optical module, method of manufacturing the optical module, and data communication system including the optical module

ABSTRACT

An optical module includes a fiber array, a laser diode array and a photodiode array. The fiber array has optical fibers which are divided to a transmitter group and a receiver group. The laser diode array has laser diodes which are grouped in a transmitter group. The photodiode array has photodiodes which are divided to a monitor group and a receiver group. The laser diode array is provided between the fiber array and the photodiode array. Each optical fiber of the transmitter group, each laser diode of the transmitter group and each photodiode of the monitor group are optically aligned, respectively. Each optical fiber of the receiver group is optically aligned with each photodiode of the receiver group, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 11/046,875, filed Feb. 1, 2005. The entire contents of that application are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical module, a method of manufacturing the optical module, and a data communication system including the optical module.

2. Discussion of the Background

U.S. Patent Application Publication No. US2002/0114590 A1 discloses an optical interface for a 4-channel opto-electronic transmitter-receiver module. The optical interface for the 4-channel opto-electronic transmitter-receiver module includes a module housing, a transmitter chip, a receiver chip and an adapter unit. The module housing includes at least one housing wall, and is provided with a wall opening in the housing wall. The transmitter chip includes a 4-channel laser diode array, and the receiver chip includes a 4-channel photodetector array. The transmitter chip and the receiver chip are mounted in the wall opening. The adapter unit includes eight optical fibers, each of which has a proximal fiber end and an opposite fiber end.

Proximal fiber ends of the optical fibers are grouped in two fiber end arrays. Each of the two fiber end arrays is supported in optical alignment with a corresponding one of the 4-channel laser diode array and the 4-channel photodetector array. Each of the two fiber end arrays includes four fiber ends evenly spaced apart from each other. The two fiber end arrays are spaced apart from each other by a distance greater than spacing between adjacent optical fibers in each of the two fiber end arrays.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an optical module includes a fiber array, a laser diode array and a photodiode array. The fiber array has optical fibers which are divided to a transmitter group and a receiver group. The laser diode array has laser diodes which are grouped in a transmitter group. The photodiode array has photodiodes which are divided to a monitor group and a receiver group. The laser diode array is provided between the fiber array and the photodiode array such that each end surface of the optical fibers of the transmitter group faces each laser diode of the transmitter group. Each optical fiber of the transmitter group, each laser diode of the transmitter group and each photodiode of the monitor group are optically aligned, respectively. Each optical fiber of the receiver group is optically aligned with each photodiode of the receiver group, respectively.

According to another aspect of the present invention, a method of manufacturing an optical module includes positioning a laser diode submount, which is provided with a laser diode array, onto a bridge, which is provided with a terminal block, and connecting one end of a laser diode lead wire to the laser diode array and another end of the laser diode lead wire to a bonding pad of the terminal block. In this method, each optical fiber of a transmitter group of a fiber array is optically aligned with each corresponding laser diode of a transmitter group. Then, the fiber array is connected to the laser diode submount. Each optical fiber of a transmitter group and a receiver group of a mechanical transfer ferrule is optically aligned with each corresponding photodiode of a monitor group and a receiver group of a photodiode array which is provided on a photodiode submount. Then, the mechanical transfer ferrule is connected to the photodiode submount. The fiber array, which is connected with the laser diode submount provided with the laser diode array, is connected with the mechanical transfer ferrule, which is connected with the photodiode submount provided with the photodiode array, using a guide pin such that each optical fiber of the transmitter group of the fiber array, each laser diode of the transmitter group, each optical fiber of the transmitter group of the mechanical transfer ferrule and each photodiode of the monitor group are optically aligned, respectively, and such that each optical fiber of a receiver group of the fiber array, each optical fiber of the receiver group of the mechanical transfer ferrule and each photodiode of the receiver group are optically aligned, respectively.

According to yet another aspect of the present invention, a data communication system includes an optical module which has a fiber array, a laser diode array and a photodiode array. The fiber array has optical fibers which are divided to a transmitter group and a receiver group. The laser diode array has laser diodes which are grouped in at least a transmitter group. The photodiode array has plural photodiodes which are divided to a monitor group and a receiver group. The laser diode array is provided between the fiber array and the photodiode array such that each end surface of the optical fibers of the transmitter group faces each laser diode of the transmitter group. Each optical fiber of the transmitter group, each laser diode of the transmitter group and each photodiode of the monitor group are optically aligned, respectively. Each optical fiber of the receiver group is optically aligned with each photodiode of the receiver group, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a top plan view of an optical module according to an embodiment of the present invention;

FIG. 2 is a cross sectional view of the optical module cut along the line II-II of FIG. 1;

FIG. 3 is a cross sectional view of the optical module cut along the line III-III of FIG. 1;

FIG. 4 is a top plan view of an optical module according to an embodiment of the present invention;

FIG. 5 is a cross sectional view of the optical module cut along the line V-V of FIG. 4;

FIG. 6 is an end view of the optical module in FIG. 4;

FIG. 7 is a top plan view of an optical module according to an embodiment of the present invention;

FIG. 8 is a cross sectional view of the optical module cut along the line VIII-VIII of FIG. 7;

FIG. 9 is a top plan view of an optical module according to an embodiment of the present invention;

FIG. 10 is a cross sectional view of the optical module cut along the line X-X of FIG. 9;

FIG. 11 is showing a method of manufacturing an optical module according to the present invention;

FIG. 12 is a side view of an optical module according to an embodiment of the present invention; and

FIG. 13 is showing a data communication system according to an embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings.

FIGS. 1-3 show an optical module according to an embodiment of the present invention. Referring to FIGS. 1-3, the optical module 2 includes, a multi-channel, for example, 8-channel fiber array 4, a multi-channel, for example, 4-channel laser diode array 6, a laser diode submount 8, a multi-channel, for example, 8-channel photodiode array 10, and a photodiode submount 14.

The laser diode array 6 is bonded on the laser diode submount 8. The photodiode array 10 is bonded to the photodiode submount 14. The fiber array 4 and the photodiode submount 14 are connected to sandwich the laser diode submount 8. A spacer 16 is provided between the photodiode submount 14 and the laser diode submount 8 to tilt the photodiode array, with a predetermined angle, away from the fiber array 4 to reduce unwanted back reflection, caused by the photodiode array 10, into optical fibers of the fiber array. The spacer 16 has a thickness of, for example, about 200 μm and is made of, for example, a resin material. The phrase “about 200 μm” includes reasonable measuring margins of error accepted by persons skilled in the art. This use of “about” is applicable throughout this specification.

The fiber array 4 includes eight optical fibers 4 a-4 h extending through the fiber array 4. The fiber array 4 is divided to a transmitter group which includes first to fourth optical fibers 4 a-4 d, and a receiver group which includes fifth to eighth optical fibers 4 e-4 h. The laser diode array 6 includes first to fourth laser diodes 6 a-6 d which are grouped together as a transmitter group. The photodiode array 10 includes eight photodiodes which are divided to a monitor group including first to fourth photodiodes 10 a-10 d and a receiver group including fifth to eighth photodiodes 10 e-10 h.

The fiber array 4, the laser diode array 6, and the photodiode array 10 are arranged such that the first to fourth optical fibers 4 a-4 d of the transmitter group, the first to fourth laser diodes 6 a-6 d of the transmitter group and the first to fourth photodiodes 10 a-10 d of the monitor group are optically aligned, respectively, and the fifth to eighth optical fibers 4 e-4 h of the receiver group and the fifth to eighth photodiodes 10 e-10 h of the receiver group are optically aligned, respectively.

A distance between each of end surfaces of the optical fibers 4 a-4 d of the transmitter group and each corresponding one of the laser diodes 6 a-6 d of the transmitter group is at least about 10 μm and at most about 50 μm, preferably at least about 20 μm and at most about 30 μm. A distance between each of the laser diodes 6 a-6 d of the transmitter group and each corresponding one of the photodiodes 10 a-10 d of the monitor group is at least about 20 μm at most about 100 μm. A distance between each of end surfaces of the optical fibers 4 e-4 h of the receiver group and each corresponding one of the photodiodes 10 e-10 h of the receiver group is at least about 170 μm and at most about 500 μm.

According to this embodiment of the present invention, the eight optical fibers 4 a-4 h, the four laser diodes 6 a-6 d and the eight photodiodes 10 a-10 h have substantially equal pitches which are at least about 125 μm. In addition, a combined number of the optical fibers of the transmitter group and the receiver group of the fiber array 4 is eight, which is equal to a combined number of the photodiodes of the monitor group and the receiver group, and twice a number of the laser diodes of the transmitter group. Moreover, the eight optical fibers 4 a-4 h of the fiber array are equally divided to the transmitter group and the receiver group, and the eight photodiodes 10 a-10 h are equally divided to the transmitter group and the receiver group.

However, the pitches between the optical fibers 4 a-4 h, the laser diodes 6 a-6 d and the photodiodes 10 a-10 h may be arranged such that, for example, a pitch within one group of the fiber array 4 is different from a pitch within another group of the fiber array 4, or a pitch between the transmitter group and the receiver group of the fiber array 4 is different from a pitch within the transmitter group and the receiver group of the fiber array.

Further, the fiber array 4 may have any plural number of optical fibers and may be divided to more groups than the transmitter group and the receiver group. The photodiode array 10 may have any plural number of photodiodes and may be divided to more groups than the monitor group and the receiver group. The optical fibers and the photodiodes may be divided to plural groups unevenly, as long as each optical fiber of the transmitter group, each corresponding laser diode of the transmitter group and each corresponding photodiode of the monitor group can be optically aligned, respectively, and as long as each optical fiber of the receiver group can be optically aligned with each corresponding photodiode of the receiver group. A group or groups other than the transmitter group and the receiver group of the fiber array 4 may have one or more functions different from either or both the transmitter group and the receiver group of the fiber array 4, and a group or groups other than the monitor group and the receiver group of the photodiode array 10 may have one or more 3 functions different from either or both the monitor group and the receiver group of the photodiode array 10.

Similarly, the laser diode array 6 may have one laser diode or any plural number of laser diodes. The laser diode array 6 may be divided to more groups than the transmitter group, and may be divided to plural groups unevenly, as long as each optical fiber of the transmitter group, each corresponding laser diode of the transmitter group and each corresponding photodiode of the monitor group can be optically aligned, respectively. A group or groups of the laser diode array 6 other than the transmitter group may have one or more functions different from the transmitter group of the laser diode array 6.

Moreover, according to this embodiment of the present invention, the transmitter group and the receiver group of the fiber array 4 are adjacent to each other, and the monitor group and the receiver group of the photodiode array 10 are adjacent to each other. In addition, the fiber array 4 and the photodiode array 10 each have a single tier including a first part and a second part. In the fiber array 4, the optical fibers 4 a-4 d of the transmitter group are in the first part, and the optical fibers 4 e-4 h of the receiver group are in the second part. In the photodiode array 10, the photodiodes 10 a-10 d of the monitor group are in the first part, and the photodiodes 10 e-10 h of the receiver group are in the second part.

However, one or more optical fibers or one or more different components of the optical module may be provided between the transmitter group and the receiver group of the fiber array 4. Consequently, the photodiode array 10 may have one or more photodiodes or one or more different components of the optical module between the monitor group and the receiver group. The monitor group and the receiver group of the photodiode array 10 may be simply spaced a part in order to be in optical alignment with the fiber array 4. Further, the first part of the fiber array 4 and the first part of the photodiode array 10 may be either side of the second part of the fiber array 4 and the second part of the photodiode array 10, as long as the transmitter group and the receiver group of the fiber array 4 are optically aligned with the monitor group and the receiver group of the photodiode array 10, respectively.

According to this embodiment of the present invention, a transmitter circuit 18 is connected to the laser diode 6 a-6 d of the transmitter group and to the photodiodes 10 a-10 d of the monitor group. A receiver circuit 20 is connected to the photodiodes 10 e-10 h of the receiver group. The transmitter circuit 18 controls the laser diodes 6 a-6 d to emit optical signals according to electrical signals to be transmitted being input to the transmit circuit 18 via signal input lines 18 a-18 d. The photodiodes 10 a-10 d of the monitor group receive optical signals emitted from the laser diodes 6 a-6 d of the transmitter group, and output received optical signals to the transmitter circuit 18 to perform feed back control of the laser diodes 6 a-6 d. The photodiodes 10 e-10 h of the receiver group receive optical signals transmitted via the optical fibers 4 e-4 h of the receiver group, convert received optical signals to electrical signals, and output the electrical signals to the receiver circuit 20.

According to this embodiment of the present invention, the pitches of the optical fibers 4 a-4 h of the fiber array 4, the laser diodes 6 a-6 d of the laser diode array 6 and the photodiodes 10 a-10 h of the photodiode array 10 are substantially equal. In addition, on a single substrate of the photodiode array 10, the photodiodes 10 a-10 d of the monitor group and the photodiodes 10 e-10 h of the receiver group can be positioned together, and perform functions of both independent monitoring of the optical output power of each of the laser diodes 6 a-6 d of the transmitter group, and receiving optical signals from the optical fibers 4 e-4 h of the receiver group.

As a result, for transmitting and receiving optical signals, the optical module according to this embodiment of the present invention can increase, within limited space, a number of channels which are provided with optical output power monitors. Moreover, according to this embodiment of the present invention, structures of an optical module can be simplified, and manufacturing cost of an optical module can be reduced.

FIGS. 4-6 show an optical module according to an embodiment of the present invention which includes a two tiered multi-channel fiber array and a two tiered multi-channel photodiode array. Referring to FIGS. 4-6, the optical module 32 includes, a two tiered multi-channel, for example, 16-channel fiber array 34, a multi-channel, for example, 8-channel laser diode array 36, a laser diode submount 38, a two tiered multi-channel, for example, 16-channel photodiode array 40, and a photodiode submount 44.

The two tiered fiber array 34 is provided with a first tier and a second tier. First to eighth optical fibers 34 a-34 h in the first tier are in a transmitter group, and ninth to sixteenth optical fibers 34 i-34 p in the second tier are in a receiver group. The laser diode array 36 includes first to eighth laser diodes 36 a-36 h grouped as a transmitter group. The two tiered photodiode array 40 is provided with a first tier and a second tier. First to eighth photodiodes 40 a-40 h in the first tier are in a monitor group, and ninth to sixteenth photodiodes 40 i-40 p in the second tier are in a receiver group.

Pitches between each optical fiber of the first tier and each optical fiber of the second tier directly above the each optical fiber of the first tier, for example, between an optical fiber 34 a and an optical fiber 34 i, between each photodiode of the first tier and each photodiode of the second tier directly above the each photodiode of the first tier, between eight optical fibers of each of the transmitter group and the receiver group of the fiber array, between eight laser diodes of the transmitter group of the laser diode array, and between eight photodiodes of each of the monitor group and the receiver group of the photodiode array are substantially equal, and at least about 125 μm.

The fiber array 34, the laser diode array 36 and the photodiode array 40 are arranged such that the first to eighth optical fibers 34 a-34 h of the transmitter group, the first to eighth laser diodes 36 a-36 h of the transmitter group and the first to eighth photodiodes 40 a-40 h of the monitor group are optically aligned, respectively, and the ninth to sixteenth optical fibers 34 i-34 p of the receiver group and the ninth to sixteenth photodiodes 40 i-40 p of the receiver group are optically aligned, respectively. Each of the first to eighth photodiodes 40 a-40 h of the monitor group in the first tier receives optical output power of each of the first to eighth laser diodes 36 a-36 h of the transmitter group, respectively, and each of the ninth to sixteenth photodiodes 40 i-40 p of the receiver group in the second tier receives optical signals from each of the optical fibers 34 i-34 p of the receiver group, respectively.

According to this embodiment of the present invention, the first tier and the second tier of the fiber array are in a lower tier and an upper tier, respectively, and are adjacent to each other. The first tier and the second tier of the photodiode array are in a lower tier and an upper tier, respectively, and are adjacent to each other. However, the first tier may be upper in relation to the second tier in the fiber array and the photodiode array. In addition, one or more tiers of optical fibers or photodiodes, or one or more of other components of the optical module may be provided between the first tier and the second tier in either or both the fiber array and the photodiode array. Further, the laser diode array may have one or more groups in one or more tiers other than a tier of the transmitter group, as long as each optical fiber of the transmitter group, each corresponding laser diode of the transmitter group and each corresponding photodiode of the monitor group can be optically aligned, respectively, and as long as each optical fiber of the receiver group can be optically aligned with each corresponding photodiode of the receiver group.

Moreover, the fiber array and the photodiode array may have any plural optical fibers and any plural photodiodes, respectively, and may be divided, evenly or unevenly, to plural groups in plural tiers. The laser diode array may have one or more laser diodes, and may be grouped, evenly or unevenly, in one or more groups in one or more tiers, as long as the optical fibers of the transmitter group, the laser diodes of the transmitter group, the photodiodes of the monitor group are optically aligned, respectively, and the optical fibers of the receiver group and the photodiodes of the receiver group are optically aligned, respectively.

According to this embodiment of the present invention, the fiber array and the photodiode array can be arranged such that the pitches between each optical fiber of the first tier and each optical fiber of the second tier directly above the each optical fiber of the first tier, between each photodiode of the first tier and each photodiode of the second tier directly above the each photodiode of the first tier, between the eight optical fibers of each of the transmitter group and the receiver group of the fiber array, between the eight laser diodes of the transmitter group of the laser diode array, and between the eight photodiodes of each of the monitor group and the receiver group of the photodiode array are substantially equal. In addition, on a single substrate of the photodiode array, the photodiodes of the monitor group and the receiver group can be positioned adjacent to each other, and perform functions of both independent monitoring of the optical output power of each of the laser diodes 36 a-36 h of the transmitter group, and receiving the optical signals from the optical fibers 34 i-34 p of the receiver group.

As a result, the optical module according to this embodiment of the present invention can increase, within limited space, a number of channels which are provided with optical output power monitors. Moreover, according to this embodiment of the present invention, structures of an optical module can be simplified, and manufacturing cost of an optical module can be reduced.

FIGS. 7 and 8 show an optical module according to an embodiment of the present invention which includes a mechanical transfer ferrule. Referring to FIGS. 7-8, the optical module 62 includes, a multi-channel, for example, 8-channel fiber array 64, a multi-channel, for example, 4-channel laser diode array 66, a laser diode submount 68, a multi-channel, for example, 8-channel photodiode array 70, a photodiode submount 74, and the mechanical transfer ferrule 80 with plural, for example, 8 optical fibers.

The fiber array 64 and the laser diode submount 68, and the laser diode submount 68 and the mechanical transfer ferrule 80 are bonded to each other to sandwich the laser diode array 66 by the fiber array 64 and the mechanical transfer ferrule 80. In addition, the fiber array 64 and the mechanical transfer ferrule 80 are connected by two guide pins 82 to sandwich the laser diode array 66 and the laser diode submount 68. A spacer 76 is provided between the mechanical transfer ferrule 80 and the photodiode submount 74 to provide space for the photodiode array 70 which is bonded on the photodiode submount 74. A photodiode lead wire 88 connects the photodiode array 70 to electrical circuits 90 to supply electrical currents and to receive electrical signals. A laser diode lead wire 86 connects the laser diode array 66 to the electrical circuits 90 to supply electrical currents and to receive electrical signals.

The fiber array 64 includes first to fourth optical fibers 64 a-64 d of a transmitter group, and fifth to eighth optical fibers 64 e-64 h of a receiver group. The laser diode array 66 includes first to fourth laser diodes 66 a-66 d of a transmitter group. The photodiode array 70 includes first to fourth photodiodes 70 a-70 d of a monitor group, and fifth to eighth photodiodes 70 e-70 h of a receiver group. The mechanical transfer ferrule 80 includes first to fourth optical fibers 80 a-80 d of a transmitter group and fifth to eighth optical fibers 80 e-80 h of a receiver group.

The fiber array 64, the laser diode array 66, the mechanical transfer ferrule 80, and the photodiode array 70 are arranged such that the first to fourth optical fibers 64 a-64 d of the transmitter group of the fiber array, the first to fourth laser diodes 66 a-66 d of the transmitter group, the first to fourth optical fibers 80 a-80 d of the transmitter group of the mechanical transfer ferrule, and the first to fourth photodiodes 70 a-70 d of the monitor group are optically aligned along an optical axis direction of transmitter groups, respectively, and such that the fifth to eighth optical fibers 64 e-64 h of the receiver group of the fiber array, the fifth to eighth optical fibers 80 e-80 h of the receiver group of the mechanical transfer ferrule, and the fifth to eighth photodiodes 70 e-70 h of the receiver group are optically aligned along an optical axis direction of receiver groups, respectively. A length of the mechanical transfer ferrule 80 along each of the optical axis direction of transmitter groups and the optical axis direction of receiver groups is, for example, at least about 1 mm.

Here, each pair of the transmitter group and the receiver group of the fiber array, the monitor group and the receiver group of the photodiode array, and the transmitter group and the receiver group of the mechanical transfer ferrule are adjacent to each other within a respective pair. However, one or more groups of optical fibers or one or more of other components of the optical module may be provided between the transmitter group and the receiver group of the fiber array. Similarly, one or more groups of photodiodes or one or more of other components of the optical module may be provided between the monitor group and the receiver group of the photodiode array, and one or more groups of optical fibers or one or more of other components of the optical module may be provided between the transmitter group and the receiver group of the mechanical ferrule, as long as the optical fibers of the transmitter group of the fiber array, the laser diodes of the transmitter group, the optical fibers of the transmitter group of the mechanical ferrule and the photodiodes of the monitor group are optically aliened, respectively, and the optical fibers of the receiver group of the fiber array, the optical fibers of the receiver group of the mechanical ferrule and the photodiodes of the receiver group are optically aligned, respectively.

According to this embodiment of the present invention, because each of the optical fibers of the transmitter group 80 a-80 d and the receiver group 80 e-80 h of the mechanical transfer ferrule has a numerical aperture of at most about 0.21, the mechanical transfer ferrule 80 can reduce optical crosstalk between optical signals emitted from the laser diodes 66 a-66 d of the transmitter group to be received by the photodiodes 70 a-70 d of the monitor group, respectively. The mechanical transfer ferrule 80 can also reduce optical crosstalk between the laser diodes 66 a-66 d of the transmitter group and the optical fibers 64 e-64 h of the receiver group of the fiber array.

Moreover, because the mechanical transfer ferrule separates a point where the photodiode lead wire 88 is connected to the photodiode array from a point where the laser diode lead wire 86 is connected to the laser diode array, providing a distance of, for example, at least about 1 mm, electrical crosstalk between the photodiode lead wire 88 and the laser diode lead wire 86 can be reduced, thereby allowing the electrical circuits 90 to accurately receive electrical signals via the photodiode lead wire 88 and the laser diode lead wire 86.

Further, because the mechanical transfer ferrule 80 and the fiber array 64 are connected by the two guide pins 82, the mechanical transfer ferrule 80 can be precisely positioned in relation to the fiber array 64, and can also increase bonding strength between the laser diode submount 68 and the fiber array 64. Because of the two guide pins 82, the bonding strength between the laser diode submount 68 and the fiber array 64 can be increased to pass a temperature cycle test at −40° C., 85° C. and 500 cycles, and a high temperature and high humidity storage test at 85° C., 85% and 5,000 hours.

As a result, the optical module according to this embodiment of the present invention can increase, within limited space, a number of channels which are provided with optical output power monitors, and can also stabilize transmission and reception of optical signals. In addition, because use of the two guide pins increases the bonding strength between the laser diode submount and the fiber array, the optical module can be used even under an environment with either or both a high temperature and a high humidity. Moreover, structures of an optical module can be simplified, and manufacturing cost of an optical module can be reduced.

FIGS. 9 and 10 show an optical module according to an embodiment of the present invention which includes a shield metal. Referring to FIGS. 9 and 10, the optical module 102 includes, a multi-channel, for example, 8-channel fiber array 104, a multi-channel, for example, 4-channel laser diode array 106, a laser diode submount 108, a multi-channel, for example, 8-channel photodiode array 110, a photodiode submount 114, a mechanical transfer ferrule 120 with plural, for example, 8 optical fibers, and the shield metal 124.

The shield metal 124 is provided near a photodiode lead wire 128, bonded onto a surface of the mechanical transfer ferrule 120, and sandwiched by the photodiode array 110 and the mechanical transfer ferrule 120. The shield metal 124 may be between the laser diode array 106 and the mechanical transfer ferrule 120. A laser diode lead wire 126 connects the laser diode array 106 to electrical circuits 130. The photodiode lead wire 128 connects the photodiode array 110 to the electrical circuits 130.

According to this embodiment of the present invention, the shield metal 124 prevents electrical crosstalk between the photodiode lead wire 128 and the laser diode lead wire 126, which affects the photodiode lead wire 128, thereby increasing accuracy of electrical signals which the electrical circuits 130 receive from the photodiode array 110 via the photodiode lead wire 128. In addition, the mechanical transfer ferrule 120 coated by metal or made from metal coated plastics can also prevents the electrical crosstalk between the photodiode lead wire 128 and the laser diode lead wire 126, thereby increasing the accuracy of the electrical signals which the electrical circuits 130 receive from the photodiode array 110 via the photodiode lead wire 128.

As a result, the optical module according to this embodiment of the present invention can increase, within limited space, a number of channels which are provided with optical output power monitors, and can also stabilize transmission and reception of optical signals. In addition, because use of at least one guide pin to connect the mechanical transfer ferrule and the fiber array increases bonding strength between the laser diode submount and the fiber array, the optical module can be used even under an environment with either or both a high temperature and a high humidity. Moreover, according to this embodiment of the present invention, structures of an optical module can be simplified, and manufacturing cost of an optical module can be reduced.

FIG. 11 shows a method of manufacturing an optical module according to an embodiment of the present invention which includes a bridge and a terminal block on the bridge. Referring to FIG. 11, the optical module 142 includes, a multi-channel fiber array 144, a multi-channel laser diode array 146, a laser diode submount 148, a multi-channel photodiode array 150, a photodiode submount 154, a multi-channel mechanical transfer ferrule 160, the bridge 172 and the terminal block 174.

The bridge 172 connects with the laser diode submount 148. The laser diode submount 148 has a thickness of at least about 150 μm and at most about 350 μm. The bridge 172 is provided with an opening so that optical signals transmitted from laser diodes of a transmitter group of the laser diode array 146 and from optical fibers of a receiver group of the fiber array can pass through to be received by corresponding photodiodes of a monitor group and a receiver group of the photodiode array 150, without being attenuated. The terminal block 174, which is provided on the bridge 172, has a bonding pad 176 to bond one end of a laser diode lead wire 166 to the terminal block 174. The mechanical transfer ferrule 160 is connected with the bridge 172 and the photodiode array 150 to be sandwiched by the bridge 172 and the photodiode array 150. The fiber array 144, the laser diode array 146, the mechanical transfer ferrule 160 and the photodiode array 150 are optically aligned, respectively.

According to this embodiment of the present invention, because the laser diode submount 148 is provided with the bridge 172 and the terminal block 174, the laser diode lead wire 166 can be bonded to the laser diode array 146 without a need of a special tool, even when the laser diode submount 148 is with a thickness of, for example, about 150 μm. As a result, the optical module according to this embodiment of the present invention can reduce manufacturing cost.

In the manufacturing of the optical module according to the present invention, in a process A, the laser diode submount 148, on which the laser diode array 146 is provided, is positioned on the bridge 172, on which the terminal block 174 is provided. Then, one end of the laser diode lead wire 166 is bonded to the laser diode array 146 and another end of the laser diode lead wire 166 to the bonding pad 176 of the terminal block 174.

In a process B, each optical fiber of a transmitter group of the fiber array 144 is optically aligned with each corresponding laser diode of the transmitter group of the laser diode array 146. Then, the fiber array 144 is bonded to the laser diode submount 148 with the laser diode array 146, which is positioned on the bridge 172 during the process A.

In a process C, each optical fiber of a transmitter group and a receiver group of the mechanical transfer ferrule 160 is optically aligned with each corresponding photodiode of the monitor group and the receiver group of the photodiode array 150. Then, the mechanical transfer ferrule 160 is bonded to the photodiode submount 154 with the photodiode array 150.

In a process D, the mechanical transfer ferrule 160, onto which the photodiode submount 154 is bonded during the process C, is connected with the fiber array 144, onto which the laser diode submount 148 is bonded during the process B, using at least one guide pin 162, such that each optical fiber of the transmitter group of the fiber array, each laser diode of the transmitter group, each optical fiber of the transmitter group of the mechanical transfer ferrule and each photodiode of the monitor group are optically aligned, respectively, and such that each optical fiber of the receiver group of the fiber array, each optical fiber of the receiver group of the mechanical transfer ferrule and each photodiode of the receiver group are optically aligned, respectively.

According to this method of manufacturing an optical module of the present invention, because the laser diode submount 148 is provided with the bridge 172 and the terminal block 174, the laser diode lead wire 166 can be bonded to the laser diode array 146 without a need of a special tool, even when the laser diode submount 148 is with a thickness of, for example, about 150 μm. As a result, the optical module according to this embodiment of the present invention can reduce manufacturing cost.

FIG. 12 shows an optical module according to an embodiment of the present invention which includes a flexible cable. Referring to FIG. 12, the optical module 202 includes a multi-channel fiber array 204, a multi-channel laser diode array 206, a laser diode submount 208, a multi-channel photodiode array 210, a mechanical transfer ferrule 220, and the flexible cable 240.

The flexible cable 240, which replaces a photodiode submount, is provided with a shield metal layer 242 on one side, and a trace photodiode 244 on an opposite side to the side with the shield metal layer 242. The trace photodiode 244 has an opening through which optical signals, emitted by laser diodes of the laser diode array 206 and by optical fibers of the fiber array 204, can pass to be received by corresponding photodiodes of the photodiode array 210, without being attenuated. The shield metal layer 242 of the flexible cable is positioned so that electrical crosstalk between a laser diode lead wire 226 and the trace photodiode 244 is prevented.

According to this embodiment of the present invention, the flexible cable 240 includes functions of a photodiode submount, a spacer between the laser diode array 206 and the photodiode array 210 or between the photodiode array 210 and a shield metal, a shield metal between the laser diode array 206 and the photodiode array 210, and a photodiode lead wire which connects the photodiode array 210 to electrical circuits 230.

As a result, the optical module according to this embodiment of the present invention can be manufactured with fewer parts, can increase within limited space a number of channels which are provided with optical output power monitors, and can also stabilize transmission and reception of optical signals. In addition, because use of at least one guide pin to connect the mechanical transfer ferrule and the fiber array increases bonding strength between the laser diode submount and the fiber array, the optical module can be used even under an environment with either or both a high temperature and a high humidity. Moreover, according to this embodiment of the present invention, structures of an optical module can be simplified, and manufacturing cost of an optical module can be reduced.

FIG. 13 shows a data communication system according to an embodiment of the present invention. Referring to FIG. 13, the data communication system 300 includes at least one optical module 302, which is, for example, an optical module shown in FIGS. 1-3. Fiber ends 350 of a fiber array 314 of the optical module 302 are connected to fiber ends 390 of a communication fiber array 374. Another fiber ends 392 of the communication fiber array 374 are connected to a data communication module 362. The data communication system 300 according to this embodiment of the present invention may include other optical modules shown in FIGS. 4-6, FIGS. 7-8, FIGS. 9- 10, FIG. 11 and FIG. 12. The data communication system 300 may be, for example, an intermediate optical fiber communication system or a part of the intermediate optical fiber communication system. A service provider of the intermediate optical fiber communication system, which has many individual subscribers, may be required to carry, for example, one thousand of multi-channel optical modules at a node of a base station of the service provider. According to this embodiment of the present invention, because the optical module 302 can increase, within limited space, a number of channels to transmit and receive information, a size of the data communication system 300 can be decreased. The data communication system 300 can also be at least a part of, for example, a satellite communication system, a telecommunication system, a visual image communication system or a computer data communication system.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. 

1. An optical module comprising: a fiber array including plural optical fibers which are divided to at least a transmitter group and a receiver group; a laser diode array including plural laser diodes which are grouped in at least a transmitter group; a photodiode array including plural photodiodes which are divided to at least a monitor group and a receiver group, the laser diode array being provided between the fiber array and the photodiode array such that each of end surfaces of the plural optical fibers of the transmitter group faces each of the plural laser diodes of the transmitter group, each of the plural optical fibers of the transmitter group, each of the plural laser diodes of the transmitter group and each of the plural photodiodes of the monitor group being optically aligned, respectively, and each of the plural optical fibers of the receiver group being optically aligned with each of the plural photodiodes of the receiver group, respectively; and a mechanical transfer ferrule having plural optical fibers which are divided to at least a transmitter group and a receiver group and which are provided between the laser diode array and the photodiode array, each of the plural optical fibers of the transmitter group of the fiber array, each of the plural laser diodes of the transmitter group, each of the plural optical fibers of the transmitter group of the mechanical transfer ferrule and each of the plural photodiodes of the monitor group being optically aligned along an optical axis direction of transmitter groups, respectively, and each of the plural optical fibers of the receiver group of the fiber array, each of the plural optical fibers of the receiver group of the mechanical transfer ferrule and each of the plural photodiodes of the receiver group being optically aligned along an optical axis direction of receiver groups, respectively.
 2. The optical module according to claim 1, wherein the fiber array has a first tier and a second tier, plural optical fibers provided in the first tier are in the transmitter group, plural optical fibers provided in the second tier are in the receiver group, the photodiode array has a first tier and a second tier, plural photodiodes provided in the first tier are in the monitor group, and plural photodiodes provided in the second tier are in the receiver group.
 3. The optical module according to claim 2, wherein, a pitch between each of the plural optical fibers of the first tier and each of the plural optical fibers of the second tier next to each other and a pitch between each of the plural photodiodes of the first tier and each of the plural photodiodes of the second tier next to each other are substantially equal and at least about 125 μm.
 4. The optical module according to claim 1, wherein the transmitter group and the receiver group of the fiber array are adjacent to each other, the monitor group and the receiver group of the photodiode array are adjacent to each other, and the transmitter group and the receiver group of the mechanical transfer ferrule are adjacent to each other.
 5. The optical module according to claim 1, wherein each of the plural optical fibers of the transmitter group and the receiver group of the mechanical transfer ferrule has a numerical aperture of at most about 0.21.
 6. The optical module according to claim 1, further comprising at least one guide pin being provided with the mechanical transfer ferrule to precisely position the mechanical transfer ferrule in relation to the laser diode array and the fiber array.
 7. The optical module according to claim 1, wherein the photodiode array is provided with a photodiode lead wire, and the laser diode array is provided with a laser diode lead wire.
 8. The optical module according to claim 1, wherein the mechanical transfer ferrule has a length of at least about 1 mm along the optical axis direction of transmitter groups and the optical axis direction of receiver groups.
 9. The optical module according to claim 1, further comprising a shield metal being provided between the laser diode array and the photodiode array.
 10. The optical module according to claim 1, wherein the mechanical transfer ferrule is coated with metal.
 11. The optical module according to claim 1, wherein the mechanical transfer ferrule is made from metal coated plastics.
 12. The optical module according to claim 1, further comprising: a laser diode submount being provided with the laser diode array; a bridge being provided with the laser diode submount and being arranged to allow optical signals, emitted from the transmitter group of the laser diode array and from the receiver group of the fiber array, to pass through without being attenuated; a terminal block having a bonding pad and being provided with the bridge; and a laser diode lead wire one end of which is bonded to the bonding pad of the terminal block.
 13. The optical module according to claim 12, wherein the laser diode submount has a thickness of at least about 150 μm and at most about 350 μm.
 14. The optical module according to claim 1, further comprising a flexible cable being provided with the photodiode array and being arranged to allow optical signals, emitted from the transmitter group of the laser diode array and from the receiver group of the fiber array, to pass through without being attenuated.
 15. The optical module according to claim 14, wherein the laser diode array is provided with a laser diode lead wire, and the flexible cable is provided with a shield metal layer on one side and a trace photodiode on an opposite side to the side with the shield metal layer.
 16. A method of manufacturing an optical module comprising: positioning a laser diode submount provided with a laser diode array onto a bridge provided with a terminal block; connecting one end of a laser diode lead wire to the laser diode array and another end of the laser diode lead wire to a bonding pad of the terminal block; connecting a fiber array to the laser diode submount so that each of plural optical fibers of a transmitter group of the fiber array is optically aligned with each corresponding one of plural laser diodes of a transmitter group of the laser diode array provided on the laser diode submount; connecting a mechanical transfer ferrule to a photodiode submount so that each of plural optical fibers of a transmitter group and a receiver group of the mechanical transfer ferrule is optically aligned with each corresponding one of plural photodiodes of a monitor group and a receiver group of a photodiode array which is provided on the photodiode submount; and connecting the fiber array, which is connected with the laser diode submount provided with the laser diode array, with the mechanical transfer ferrule, which is connected with the photodiode submount provided with the photodiode array, using at least one guide pin so that each of the plural optical fibers of the transmitter group of the fiber array, each of the plural laser diodes of the transmitter group, each of the plural optical fibers of the transmitter group of the mechanical transfer ferrule and each of the plural photodiodes of the monitor group are optically aligned, respectively, and each of plural optical fibers of a receiver group of the fiber array, each of the plural optical fibers of the receiver group of the mechanical transfer ferrule and each of the plural photodiodes of the receiver group are optically aligned, respectively. 